restricted, but in Louisiana there are large catches of small shrimp. Conse- quently, for a given weight ofcatch, the ex-vessel value of white and brown.
Relationship Between Marketing Category (Count) Composition and Ex-Vessel Value of Reported Annual Catches of Shrimp in the Eastern Gulf of Mexico CHARLES W. CAILLOUET, FRANK J PATELLA, and WILLIAM B JACKSON
Introduction Caillouet and Patella (1978) showed how marketing category (count=number of shrimp per pound, heads-off) composition of the reported annual catches of brown shrimp, Penaeus aztecus, and white shrimp, P. seti[erus, influenced the value of these catches from two Gulf states, Texas and Louisiana, which have different shrimp laws (Christmas and Etzold, 1977) and shrimp harvesting strategies. In Texas, the catch of small shrimp is greatly restricted, but in Louisiana there are large catches of small shrimp. Consequently, for a given weight of catch, the ex-vessel value of white and brown shrimp harvested at larger sizes in Texas was 1.2 and 1.6 times higher, respectively, than that of white and brown shrimp harvested at smaller sizes in Louisiana. This paper extends the analysis to the shrimp fisheries of the eastern Gulf of Mexico, namely
The authors are with the Southeast Fisheries Center Galveston Laboratory, National Marine Fisheries Service, NOAA, 4700 Avenue U, Galveston, TX 77550. This paper is Contribution No. 79-14G from the Southeast Fisheries Center, Galveston Laboratory.
those of Mississippi, Alabama, and west coast of Florida, and includes pink shrimp, P, duorarum, as well as brown and white shrimp. In this paper, harvesting strategy refers to the sizes of shrimp harvested, retained, and landed.
Mav-June 1979
Shrimp fisheries of the eastern Gulf of Mexico are divided into three major statistical regions (Fig. I): Pensacola to Mississippi River (statistical areas 10-12), Apalachicola (statistical areas 7-9), and Sanibel to Tortugas (statistical areas. 1-6). These regions encompass that part of the Louisiana coast east of the Mississippi River, the coasts of Mississippi and Alabama, and the west coast of Florida. Only the dominant species in each of these three regions are considered herein. Pink
Figure I.-Statistical areas used in reporting Gulf Coast shrimp data. 90'
9S"w
.5'
'--TEXAS
- - - - ---- ..... ,.... , . )
30'
30'
N
17
A aSTRA CT- The effeet on ex-vessel value of marketing category (mul1l = number of shrimp per pound, heads-off) composition of reported annual catches 0/ hrown shrimp, Penaeus aztecus, white shrimp, P. setiferus, and pink shrimp, P, duorarum, in the eastern Gulf of Mexico. Shrimp management implications are discussed.
Brief Description of Fisheries and Data
16
15
GULf
OF
'5'
MEXICO
S"'NI~El TO
f,,3_--r-~1
TORTUGAS
, 95'
90'
85'
80'
shrimp is the dominant species in reported catches from the Apalachicola and Sanibel to Tortugas regions, and brown and white shrimp dominate the reported catches in the Pensacola to Mississippi River region (Fig. 2). The Apalachicola region appears to be a zone of transition from brown and white to pink shrimp. Brown, white, and pink shrimp spend the juvenile and subadult phases of their life cycles in inshore waters and the adult and larval phases in offshore waters (Fig. 3). They are first exploited by the inshore fisheries, then those that
survive emigrate from the estuaries and become vulnerable to the offshore fisheries. Numbers of shrimp vessels (5 net registry tons and larger, Fig. 4) and their average size (net registry tons, Fig. 5) have increased gradually in Mississippi, Alabama, and Rorida.
Numbers of shrimp boats (less than 5 net registry tons, Fig. 6) have remained relatively constant in Alabama and Rorida but have increased in Mississippi. The number of vessels is higher in Rorida than in Alabama and Mississippi (Fig. 4), and Alabama and Rorida vessels average larger than those of
Figure 3.-Relationship among inshore and offshore shrimp fisheries and estuarine and oceanic phases of brown, white, and pink shrimp life cycles. OCEANIC PHASE OF LIFE CYCLE
ESTUARINE PHASE OF LIFE CYCLE
Figure 2. -Species composition (percent by weight, heads-off) of reported annual catches of shrimp from Pensacola to Mississippi River (statistical areas 10-12), Apalachicola (statistical areas 79), and Sanibel to Tortugas (statistical areas 1-6) regions, 1959-75. PENSACOLA
-
APALACHICOLA
TO MISS RIVER
1•
10
SANIBEl TO TORTUGAS
----• - ---• 0- - • -----• o. --
10~l.
•
=
1959
=
1960
l°~l.
1961
l°l. l°l
1962 1963
l°~l.
~
Z w
w
l0j.. l°l
-
lO~l.
10~l.
O· o.
10l l°l l°l·
• •
10~l.
O· O·
100
l
•
lO~l.
IOl
z
~
"
g~
2
• ---• •• ••
~
i: ~
J::
0
z ~
•"
g~
~
w
i: ~
J::
0
--• z
~
g
196" 1965
1966
Figure 4.-Reported annual number (thousands) of shrimp vessels (5 net registry tons or larger) in Mississippi. Alabama, and Florida west coast, 1959-
73.
1967
1968
~ w
1969
V) V)
w
_ 1970 1971
FLA
> u..
o V)
o
z
1972
«
ALA
V)
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1973
o ....J:
MISS
197.4
1975 ~
:w:: t:: :I: Z J:: ~ 0: ~ 0
o
~~-~--~-~---------~-~--.-~~,
1959
1961
1963
1965
1967
1969
1971
1973
YEAR
Marine Fisheries Review
Mississippi (Fig. 5). Numbers of fishermen operating from vessels have increased in Florida and Alabama but have declined somewhat in Mississippi (Fig. 7), whereas Mississippi has larger numbers of fishermen operating from boats than either Alabama or Florida. The results of these differences and trends in characteristics of the fisheries, as well as differences in state laws and harvesting strategies, also are reflected in the count composition of the reported annual catches in the Pensacola to Mississippi River, Apalachicola, and Sanibel to Tortugas regions (Fig. 8-11).
Data and Methods This paper deals with reported annual catches of shrimp during 1959-75, the years for which annual summaries of the Gulf Coast shrimp data (National Marine Fisheries Service, 1960-76) were available. Combined inshore and offshore catches were used. They represent catches landed by U.S. craft at U.S. ports along the coast of the Gulf of Mexico. The reported catches represent only a portion of the total annual catches, since some of the commercial landings (including those of foreign craft),
Figure 5.-Annual average reported registry tons per shrimp vessel (5 net registry tons or larger) in Mississippi, Alabama, and Florida west coast, 196073. 80 70
ALA FLA
5...'" 60 >-
'"
:;; 50 _ - -_ _-MISS
...i5 '"
40 30 0 1960
1964
1962
1968
1966
1970
1972
YEAR
discarded undersized shrimp, and landings by sport fishermen are not adequately sampled and therefore are not reported (Fig. 3). The proportion of the total annual catch that is not reported is unknown, but we believe that the count composition of the reported catch is a reasonably good reflection of shrimp population characteristics and harvesting strategy combined. We used annual summaries of reported catch in pounds (heads-off) within eight marketing or count categories (number of shrimp per pound, heads-off: ~68, 51-67,41-50, 31-40, 26-30, 21-25, 15-20, and
